GENEVA (AP) — Alibaba founder Jack Ma says the trade dispute between the U.S. and China could “unfortunately” last 20 years.

However, he expressed hope a solution could be reached as a trade war would “hurt everybody.”

The Chinese e-commerce billionaire also questioned the focus among some on trade deficits, calling it a relic of the 20th century. U.S. President Donald Trump has long derided the U.S.’s whopping deficit with China.

Ma defended trade at a World Trade Organization seminar Tuesday: “When trade stops, sometimes the war starts. So trade is the way to stop wars. Trade is the way to build up trust. It’s not the weapon to fight against each other.”

Ma said the business community “should stand up and say: ‘We don’t need a war, we need business.'”